Key Topics Covered

Premise of the Diet

The idea behind the Blood Type Diet is that people have different nutritional needs based on their blood type. These include blood types O, A, B, or AB. Whether these blood types are positive or negative matters far less than the overall type for this diet. To provide an outline of the blood type diet, an explanation written by the creator of the diet is useful in understanding how it works:

“You’re born with a certain blood type. The four major blood groups are categorised based on two antigens, A and B, either being present or absent on the surface of your red blood cells. For example, someone with both antigens has AB blood, but someone with neither antigen present has O blood.

The claim is that the antigens found in your blood that decide what blood type you are, are also present in other parts of your body, including your digestive tract. That’s what causes the foods you eat to react chemically with your blood type.

The original author suggests that the first humans had type O blood. Since they were hunter-gatherers, they ate fewer carbs and more protein. Those with A blood types are believed to have descended from farmers, which is why this diet encourages more vegetables for this group. They think B blood types can digest more fat because they supposedly evolved from nomadic tribes whose diets were rich in meat and dairy.

The claim is that if you eat foods that were common when your blood type evolved, your body will digest food more efficiently.”

Analysing the Diet

  • It does largely promote nutrient rich foods that are minimally processed.
  • There’s a bit of talk of lectins being an issue. We discussed this in episode 78, and the short version is that it’s not a concern.
  • If you want to do a deeper dive into that though, like I said there is podcast episode 78 as well as a blog post I have written on the plant paradox diet which are linked in the show notes.
  • We’ve also included what foods are eaten on each diet and which to avoid in the show notes as well.
  • But essentially, the blood type diet requires some level of restriction regardless of which type of diet you are on.

Research Part 1

  • A 2014 study of 1,455 participants, found that most of the blood type diets were associated with better health markers. However, this effect was seen in everyone following the diets. Matching the ‘Blood-Type’ diets with the corresponding blood group did not change the effect size of any of these associations.

Research Part 2

  • Similarly, a 2018 study of 973 adults also found improvements in markers of health when following these diets, 
  • BUT matching a participant’s blood type (once again) did not outperform vs if they were in the “wrong” group”

Research Part 3

  • Lastly, in a 2020 study, 68 participants of different blood types ate a low fat vegan diet for 16 weeks. At the end of the 16 weeks, the researchers found no major differences in cardiometabolic changes between any of the groups.
  • This is relevant as this is at odds with the Type O diet which is higher in meat.

Summary

The general interpretation of the blood type diet is that it is heavily undermined by the research that we have discussed. However, it is good news to see that overall health improvements are seen on average but this is expected when dietary improvements are made. Specifically, diets that are more nutrient-dense and contain minimally processed foods. Although the fact that there is no link between the type of diet and the blood type in regards to outcomes, it is evident that it does not matter.

Relevant Blogs/Research

Relevant Studies:

Relevant Blogs:

Should You Go Lectin Free? Reviewing The Plant Paradox Diet 

Relevant Podcasts:

Episode 78 – Lectins | Ideal Nutrition